1. Field of the invention
This invention relates to a sludge collector flight for use in a sewage settling or sedimentation tank.
2. Discussion of the Prior Art
Sewage treatment plants contain sedimentation or settling tanks for receiving waste water. Typically such tanks include a longitudinal collector trough for receiving sewage for settling, and a cross collector trough at a discharge end of the longitudinal trough for moving the sewage to a discharge outlet from the tanks. Collector flights mounted on drive chains extending transversely of the troughs scrape sedimentation from the bottom of the tanks and skim waste from the top surface of the waste water.
Examples of cross collector flights or parts thereof are disclosed by U.S. Pat. Nos. 3,394,816, which issued to J.A. Lowry on Jul. 30, 1968; 4,663,042, which issued to Susan M. Rasper et al on May 5, 1987; 5,398,805, which issued to Frank A. Esposito et al on Mar. 21, 1995 and Re. 35,676, which issued to Stephen B. Wilcher on Dec. 2, 1997.
As mentioned above, collector flights extend transversely of a settling tank. The flights are connected to a pair of chains by brackets. Carrying/wear shoes and guiding/return shoes are mounted on the top and bottom of the flights for prolonging the life of the flights and facilitating movement of the flights in the tank by centering and guiding the flights on rails in the tank. In existing apparatuses of the above described type, the combination brackets/chain links and/or carrying/wear and guiding/return shoes are attached to the collector flights by bolts, which extend through the bodies of the flights. Thus, production of the flights is somewhat expensive, because it is necessary to extrude the flights, and then drill holes in the bodies of the flights for receiving bolts. The presence of pre-drilled holes does not allow for adjustability, i.e. varying the position of the chains with respect to the ends of the flight body. Moreover, fiberglass flights when predrilled deteriorate when exposed to water. In other words, the flights must be custom made for each tank, and each drilled hole must be treated.